(1) Field of the Invention
The present invention relates to a device for evaluating quality of granular objects including transparent or translucent pellets and rice grains, and more particularly to a device which, with respect to granular objects to which the reflection light dependent on the shapes of, for example, a pellet, influences the evaluation of the quality affected by, for example, color, enables the accurate evaluation of the shapes and quality without being influenced by the reflection light which affects in the evaluation of the quality as an obstacle.
(2) Description of the Related Art
In the case of evaluating the quality of the transparent pellet, it is known that, when the transparent pellet is irradiated by illumination light from a light source, the reflection light which has nothing to do with the quality evaluation of the transparent pellet is caused to occur from the end faces or deformed surfaces of the pellet and, when this reflection light is received by the light receiving section, the reflection light from the end faces of the pellet is known to be detected as dark light. At the light receiving section, the reflection light detected as dark light cannot be distinguished from the light which is reflected from the colored portion of the transparent pellet and is likewise detected as dark light, resulting in a mis-evaluation.
First, a conventional quality evaluation device 100 shown by FIG. 1 is explained. The device 100 comprises an illumination unit 101 equipped with a plurality of fluorescent lamps 101a-101d which constitute light sources, a light receiving section 102 disposed above the illumination unit, a light shielding plate 104 equipped with an opening 103 which is disposed between the illumination unit 101 and the light receiving section 102 and which passes a viewing line of the light receiving section 102, and a feeding means 105 which feeds granular objects and is disposed with inclination on the viewing line extended from the opening 103 of the light shielding plate 104. On the extended viewing line of the feeding means 105, there is provided a light passing hole 106 and, on the viewing line extended from the light passing hole 106, there is provided a white background 107 as a color reference plate.
In the device constructed as above, when a defective pellet having a colored portion is to be sorted from among transparent or translucent pellets, the signal waves as shown in FIG. 2 are obtained from the defective pellet. That is, in the case where the pellet is transparent, the detection is made of a detection signal S2 detected based on the light received as the dark light from both the end faces 110 of the pellet, in addition to a detection signal S1 based on the dark reflection light from the colored portion 109. In this way, from the transparent pellet 108 having a colored portion, the detection is made of the signal S2 and the signal S1 related to the two end faces 110 and the colored portion 109. In order to evaluate the colored portion 109 from changes in these signals, it is necessary to provide a means which distinguishes from each other the signals based on the end faces 110 and that based on the colored portion 109. However, since these signals both represent dark light, whatever different threshold values are set, it will be difficult to distinguish the two different signals. Thus, the evaluation by way of shapes of the transparent pellets or by counting the number of samples was more difficult. Even when the colored portion was detected, the counting of the number of pellets was not possible because the determination of a division of one pellet from another, which is transparent, was unable.
In the case of a grain in which the reflection light diffuses, the reflection light having no relation to the quality is not detected from the grain being evaluated. However, as shown in FIGS. 3 and 4, depending on the shapes of a feeding means 112 which feeds the grain, it is possible that an edge portion 114 of the opening 113 (or recess) which holds the grain causes the occurrence of the reflection light which has no relation to the quality mentioned above. The signal waves of the reflection light received then is shown in FIG. 4. It can be appreciated therefrom that the reflection light from the edge portion 114 of the feeding means separate from the reflection light from the colored portion 116 of the grain 115 is detected as the reflection light similarly as the reflection light from the colored portion 116 of the grain. That is, since the signal S4 based on the reflection light from the edge portion is detected as a signal of the same level as that of the signal S3 based on the reflection light which depends on the shape of the grain, it is not possible to evaluate the shape of the grain by the reflection light, even though the colored portion itself is detected by the signal S5 based on the colored portion by providing two threshold values.
Thus, since the quality evaluation including the shape of the grain cannot be effected at the stage where the feeding of grains is made one by one by the feeding means, the device of this kind is separately provided, in addition to the feeding means having an edge portion for feeding the grains one by one, with a disk which has recesses for feeding the grains and which enables the shape evaluation without being influenced by the edge portion. In the device of this kind, it was essential to provide separately the feeding means for feeding the grains one by one and the evaluating means for evaluating the grains fed one by one. Also, since the grain and the edge portion could not be distinguished from each other only by the feeding means as explained above, it was not possible to specify the shape of the grain.